DESCRIPTION: Seven experiments are described in this proposal to study neural activity in the olfactory bulb as the basis of stimulus coding in the olfactory system. Preliminary data indicates that isoamyl acetate and isoamyl butyrate activate the same regions of the olfactory bulb glomerular layer, but that these regions of the olfactory bulb are not activated by ethyl acetate of ethyl butyrate. This finding suggests that isoamyl may be an olfactory "primitive," "odotype," or "epitope." Experiment 1 will determine if isoamyl propionate also activates these same regions and the activation pattern by this odorant will be compared to ethyl propionate. A second part of this experiment will determine if the branched structure or number of hydrocarbons on the "O-side" of the ester bond lead to differential activation of these regions. Subsequent experiments address issues such as, is the same glomerulus activated by isoamyl acetate and isoamyl butyrate (Exp. 2) ; what is the influence of hydrophobicity on patterns of 2DG uptake (Exp.3); what is the effect of carbon chain length and terminal functional group on 2DG foci (Exp.4); what is the effect of the terminal functional group of straight-chain alphatic compounds of 6 and 8 carbons on the pattern of 2DG uptake (Exp. 5); 2DG uptake patterns resulting from stimulation with odorless compounds (Exp. 6); and changes in 2DG uptake patterns as a function of changes in concentration of stimulating compounds (Exp. 7).